Strain-relief assemblies and methods for a field-installable fiber optic connector

ABSTRACT

A strain-relief assembly for a field-installable fiber optic connector is disclosed, wherein the assembly includes a ferrule holder, an intermediate sleeve, and a crimp sleeve. The ferrule holder back section holds a buffered section of a fiber optic cable, while the ferrule holder front end holds a ferrule and a splice assembly. A stub fiber is held within the ferrule and the splice assembly so as to interface with a section of field optical fiber protruding from the buffered section. The intermediate sleeve engages and generally surrounds a portion of the ferrule holder back section and thus surrounds a portion of the buffered layer. An intermediate sleeve handler may be used to handle the intermediate sleeve and attached the intermediate sleeve to the ferrule holder back section. Stress-relief strands from the fiber optic cable are flared around the outer surface of the intermediate sleeve. A crimp sleeve is placed over the intermediate sleeve to hold the ends of the stress-relief strands in place. The crimp sleeve is then crimped, which fixes the strand ends in place and also fixes the intermediate sleeve in place on the ferrule back section.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority pursuant to 35 U.S.C. 119(3) toU.S. Provisional Application Ser. No. 60/995,568, filed Sep. 27, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fiber optic cables, and inparticular, to an assembly for providing strain-relief forfield-installable connectors for fiber optic cables.

2. Technical Background

Optical fibers are widely used in a variety of applications, includingthe telecommunications industry in which optical fibers are employed ina number of telephony and data transmission applications. Due, at leastin part, to the extremely wide bandwidth and the low noise operationprovided by optical fibers, the use of optical fibers and the variety ofapplications in which optical fibers are used are continuing toincrease. For example, optical fibers no longer serve as merely a mediumfor long distance signal transmission, but are being increasingly routeddirectly to the home or, in some instances, directly to a desk or otherwork location.

The ever increasing and varied use of optical fibers has spurred the useof field installable optical fiber connectors. Field installable opticalfiber connectors are used to terminate the ends of optical fibers, andenable quicker connection and disconnection than fusion splicing. Atypical connector holds the end of each optical fiber in a ferrule. Theconnector aligns the core of the two fibers so that light can passbetween the fiber ends, and provides a mechanical coupling to hold thetwo fiber ends together. Connectors have traditionally been one of themain concerns in using fiber optic systems because they introduce lossand because different connector types were typically not compatible.While the use of connectors was once problematic, manufacturers havestandardized and simplified them greatly. This increasinguser-friendliness has contributed to the increase in the use of fiberoptic systems.

Current field installable connectors are designed to be installed andstrain relieved on fiber cables or fiber smaller than 2.9 mm. Commoncable/fiber sizes are 900 μm tight-buffered fiber and 2.9 mm jacketedcable. A typical 2.9 mm jacketed cable consists of 900 μm tight-bufferedfiber surrounded by aramid yarn and a thin walled jacket. A need existsfor fiber optic cables having larger fiber optic cables. Unfortunately,installing field-installable connectors directly onto larger fiber opticcables is problematic given conventional connector designs. Therefore, aneed exists for new fiber optic connectors adapted for larger fiberoptic cables, as well as standard fiber optic cables that may compriseadditional and/or alternative structures.

SUMMARY OF THE INVENTION

An aspect of the invention is a strain-relief assembly for afield-installable fiber optic connector configured to support a fiberoptic cable having a buffered portion and strain-relief strands. Theassembly includes a ferrule holder having a back section with an openback end and configured to accommodate the buffered optical fiberportion. The assembly also includes an intermediate sleeve configured tosurround and engage a portion of the ferrule holder back section. Theassembly also has a crimp sleeve having an inner surface and that coversthe intermediate sleeve. The strain-relief strands are arranged betweenthe crimp sleeve inner surface and the intermediate sleeve outersurface. The crimp sleeve is crimped to capture the strain-reliefstrands between the crimp sleeve and the intermediate sleeve.

Another aspect of the invention is a method of providing strain-reliefin a connector for a fiber optic cable that has an optical fibersection, a buffer section, strain-relief strands, and a protectivejacket. The method includes inserting the optical fiber section and thebuffered section into a back section of a ferrule holder. The methodalso includes providing an intermediate sleeve having inner and outersurfaces, and engaging the intermediate sleeve with the ferrule holderback section to surround the ferrule holder back section. The methodalso includes placing a plurality of the strain-relief strands over theintermediate sleeve outer surface. The method further includes placing acrimp sleeve around the intermediate sleeve and the strain-reliefstrands and then crimping the crimp sleeve so as to secure thestrain-relief strands and to fix the intermediate sleeve onto theferrule holder back section. The method optionally includes using anintermediate sleeve handler that facilitates installing the intermediatesleeve onto the ferrule holder back section.

Another aspect of the invention is a strain-relieved connector for afiber optic cable that has an optical fiber with a front end, a bufferedlayer, and strain-relief strands. The connector includes a ferruleholder having a front section with an open front end and a back sectionhaving an open back end, wherein the open front and back ends areconnected by a ferrule holder channel. A ferrule and a splice assemblyare arranged in the ferrule holder front end, the ferrule and spliceassembly having respective central channels. A fiber stub is held withinthe ferrule and splice assembly channels, wherein the fiber stub has aback end residing in the splice assembly channel. The buffered layer isheld in the ferrule holder back section so that the fiber stub back endinterfaces with the optical fiber front end within the splice assemblychannel. The connector also includes an intermediate sleeve that engagesand surrounds a portion of the ferrule holder back end section so as tosurround the buffered layer held therein. The connector also has a crimpsleeve that is arranged around the intermediate sleeve so as to hold theends of the strain-relief strands between the crimp sleeve and theintermediate sleeve. When the crimp sleeve is crimped, it fixes thestrain-relief strands between the crimp sleeve and the intermediatesleeve and also fixes the intermediate sleeve to the ferrule holder backend.

Another aspect of the invention is an intermediate sleeve handler forholding and handling the aforementioned intermediate sleeve. The handlerincludes a C-shaped sleeve having an inner surface, an outer surface,front and back end faces, and a central hole having an central axis andconnecting the front and back end faces and sized to press fit theintermediate sleeve. A gap in the outer surface connects to the centralhole and defines the C-shape of the handler. The gap at is sized to fitover a buffered section of a fiber optic cable so that it can be placedon an off of the fiber via the exposed buffered section between thelead-in tube and the fiber optic cable. The handler includes a shelfarranged in the central hole that serves as a stop when the intermediatesleeve is press-fit into the central hole.

Additional features and advantages of the invention will be set forth inthe detailed description that follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription that follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description present embodiments of the invention,and are intended to provide an overview or framework for understandingthe nature and character of the invention as it is claimed. Theaccompanying drawings are included to provide a further understanding ofthe invention, and are incorporated into and constitute a part of thisspecification. The drawings illustrate various embodiments of theinvention, and together with the description, serve to explain theprinciples and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded side view of an example embodiment of a fiberoptic connector (“connector”) according to the present invention thatemploys the strain-relief assembly of the present invention;

FIG. 2 is a side view of the connector of FIG. 1 in the process of beingconnected to the oversized fiber optic cable shown in FIG.1;

FIG. 3A is an elevated perspective view of the intermediate sleeve, thecrimp sleeve and the ferrule holder of the strain-relief assembly of thepresent invention;

FIG. 3B is a close-up perspective view of the example embodiment of theintermediate sleeve in which the sleeve is C-shaped and threaded, andwhich has a grooved outer surface;

FIG. 4 is a side view similar to FIG. 2, but showing the intermediatesleeve threaded onto the threaded back section of the ferrule holderwhile the crimp sleeve holds the strain-relief strands out of the wayagainst the fiber optic cable;

FIG. 5 is an elevated perspective view of the connector showing thestrain-relief strands flared around the intermediate sleeve;

FIG. 6 is a side view similar to FIG. 4, illustrating the connector withthe crimp sleeve surrounding the intermediate sleeve and holdingstrain-relief strands in place on the intermediate sleeve, and alsoshowing the crimping force applied to the crimp sleeve.

FIG. 7 is an elevated perspective view of the connector similar to FIG.5, showing the crimp sleeve in place over the intermediate sleeve at thethreaded end of the ferrule holder;

FIG. 8 is a side view similar to FIG. 6, showing the housing and theboot placed over the front and back ends of the connector, respectively;

FIG. 9 is an elevated perspective view similar to FIG. 7, showing theconnector with the housing and boot in place;

FIG. 10 is perspective view of the intermediate sleeve handler of thepresent invention, along with the intermediate sleeve prior to beinginserted into the central hole of the handler; and

FIG. 11 is a perspective view similar to that of FIG. 10, but with theintermediate sleeve being held within the handler.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is now made in detail to the present preferred embodiments ofthe invention, examples of which are illustrated in the accompanyingdrawings. Whenever possible, the same reference numbers and symbols areused throughout the drawings to refer to the same or like parts. Use ofthe terms “front,” “forward,” “rear,” “rearward,” “back,” and “backward”are relative terms used for the sake of illustration.

FIG. 1 is an exploded view of an example embodiment of a fiber opticconnector (“connector”) 8 according to the present invention thatemploys the strain-relief assembly of the present invention. In anexample embodiment, fiber optic connector 8 includes many aspects incommon with the fiber optic connector described in U.S. Pat. No.7,270,487, which patent is incorporated by reference herein.

Connector 8 has a front section 8F and back section 8B. Cartesian X-Yaxes are shown for the sake of reference. FIG. 2 is a side view of theconnector of FIG. 1 in the process of being connected to an oversizedfiber optic cable 150.

Connector 8 is designed for use with an oversized fiber optic cable 150that has an optical fiber 151 made up of a field fiber 152 surrounded byone or more protective coatings 152C (e.g. a 250 μm and a 900 μmcoating). Field fiber 152 is surrounded by a strain-relief layer 156having strain-relief strands 157, and a protective outer jacket 158 thatsurrounds the strain-relief layer. Using known techniques, fiber opticcable 150 as shown in FIG. 1 has been prepared forfield-connectorization with connector 8. Fiber optic cable so preparedincludes a field optical fiber section 152S with an end 153, a buffersection 154S, and exposed strain-relief strands 157.

In an example embodiment, field optical fiber 152 has a 125 μm diameter.Also in an example embodiment, buffer layer 154 has a diameter in therange from about 250 μm to about 1 mm diameter (e.g., 900 μm), and astrain-relief layer that includes strain-relief strands 157. In anexample embodiment, strain-relief strands 157 are aramid yam and areexposed in about 15 mm lengths when cable 150 is being prepared forconnectorizing. Further, in the example embodiment, protective outerjacket 158 has an annular thickness of about 2 mm. In an exampleembodiment, fiber optic cable 150 has an overall diameter of about 4.8mm or greater, which by present-day standards is considered “oversized.”In another example embodiment, optical fiber 151 is a bend-insensitivefiber, such as a so-called “holey” fiber or a nanostructured fiber.Examples of such optical fibers are described in, for example, U.S. Pat.No. 6,243,522, pending U.S. patent application Ser. No. 11/583,098 filedOct. 18, 2006, and provisional U.S. patent application Ser. No.60/817,863 filed Jun. 30, 2006; 60/817,721 filed Jun. 30, 2006;60/841,458 filed Aug. 31, 2006; 60/841,490 filed Aug. 31, 2006; and60/879,164, filed Jan. 08, 2007 (hereinafter, “the Corning nanostructurefiber patents and patent applications”), all of which are assigned toCorning Incorporated and all of which are incorporated by referenceherein.

Connector 8 includes a ferrule 10, which in an example embodimentincludes an outer surface 12, front and back ends 14 and 16, and acentral channel 18 open at ends 14 and 16. Central channel 18 is sizedto accommodate an optical fiber such as field optical fiber 152.

Connector 8 also includes a splice assembly 20, which in an exampleembodiment accommodates a mechanical splice, that includes an uppermember 21A and a lower member 21B. Upper member 21A includes an outersurface 22A, an inner surface 23A, and front and back ends 24A and 26A.Likewise, lower member 21B includes an outer surface 22B, an innersurface 23B, and front and back ends 24B and 26B. Upper and lowermembers are brought together so that inner surfaces 23A and 23B define acentral through channel 28 sized to accommodate a field optical fibersuch as field fiber 152. Ferrule 10 and splice assembly 20 are arrangedend-to-end, as shown in FIG. 2.

Connector 8 further includes an optical fiber section 40 havingrespective front and back ends 42 and 44. Optical fiber section 40resides in channels 18 and 28 of ferrule 10 and splice assembly 20, withfiber end 42 being flush with ferrule front end 14 and fiber end 44residing in channel 28. Optical fiber section 40 serves as a “stub”fiber for the connector and so is referred to hereinafter as “stubfiber” 40.

Connector 8 further includes a ferrule holder 50 having a front section5OF and a back section 50B. Front section 5OF includes an open front end52, and back section 50B that includes an open back end 54. Ferruleholder 50 includes an outer surface 56 and a central channel (alsocalled a “ferrule bore”) 58 open at front end 52 and back end 54. In anexample embodiment, outer surface 56 includes a smooth region 62 and anouter threaded region (i.e., outer threads) 64. In an exampleembodiment, outer threads may include one or more slots 65 (FIG. 3A) tokey a cam 212 (not shown in FIG. 1; see FIG. 7).

Ferrule holder 50 is shown in FIG. 1 and in other figures as having aflared outer surface 56 for the sake of illustration. However, outersurface 56 need not be flared, such as shown in FIG. 3A, discussedbelow.

In an example embodiment, ferrule holder 50 is made of metal such asnickel silver (NiAg), which is stronger than conventional plasticferrule holders. Ferrule channel 58 includes a front section 66 havingan opening 67 at front end 52 and corresponding to surface region 62 andsized to accommodate ferrule sections 10 and splice assembly 20. Channel58 also includes a narrower back section 70 having an opening 71 at backend 54. Threads 64 are formed on ferrule back section 70, which in anexample embodiment is sized to accommodate a lead-in tube, discussedbelow. Ferrule holder 50 holds ferrule 10 and splice assembly 20 infront section 66, with front end 14 of ferrule 10 extending out fromferrule holder front end 52, as shown in FIG. 2.

Connector 8 also includes a lead-in tube 80 that has a front end 82, aflared back end 84, and a central channel 88 open at the front and backends. Central channel 88 is sized to accommodate buffer section 154S offiber optic cable 150. Lead-in tube 80 resides within ferrule holderback channel 70, with flared end 84 extending from ferrule holder backend 54 (FIG. 2). Flared end 84 facilitates the insertion of fieldoptical fiber section 152S into ferrule channels 18 and 28, and bufferedfiber section 154S into the lead-in tube. When so inserted, end 153 offield optical fiber section 152S abuts end 44 of stub fiber 40 withinchannel 28 of splice assembly 20 to define a mechanical splice, asillustrated in the inset of FIG. 2. Also, buffered fiber section 154Sresides within lead-in tube 80, also as shown in FIG. 2.

Connector 8 also includes a strain relief assembly 98, a perspectiveclose-up view of which is shown in FIG. 3A. Strain relief assembly 98includes ferrule holder 50 and an intermediate sleeve 100 having frontand back end faces 102 and 104, a central axis As, and a central hole106 centered around axis As and defined by an inner surface 107. In anexample embodiment illustrated in FIG. 3B, intermediate sleeve 100 isC-shaped and includes inner threads 108. The C-shaped intermediatesleeve 100 includes a gap 110 open to central hole 106 that defines theC-shape. Gap 110 is sized to fit over buffered portion 154. This allowsintermediate sleeve 100 to be slipped over the exposed buffered portion154 between the end of lead-in tube 80 and fiber optic cable 150 so itcan be added to connector 8 at ferrule back section 50B, as describedbelow.

Hole 106 and inner threads 108 are sized so that intermediate sleeve 100can threadedly engage the outer threads 64 of ferrule holder backsection 50B and be secured thereto. In an example embodiment,intermediate sleeve 100 has an outer surface 112 with one or moregrooves 114 running parallel to the front and back end faces 102 and104, as shown. One or more grooves 114 are configured to facilitategripping strain-relief strands 157 to provide additional strain relief,as described in greater detail below. In an example embodiment,intermediate sleeve 100 is made of aluminum. Also in an exampleembodiment, intermediate sleeve 100 is about 3.5 mm long and about 5 mmin diameter.

For the sake of discussion, intermediate sleeve 100 is discussed belowin connection with its C-shaped threaded embodiment. Other embodimentscan also be used for intermediate sleeve 100, such as for example, anon-threaded version that is otherwise fixable to the ferrule holder end(which also need not be threaded), such as through the use of asnap-connect or via an adhesive or glue. Other embodiments ofintermediate sleeve 100 include a clam-shell type design (not shown)that opens up to fit around and engage ferrule back section 50B. Stillfurther embodiments of the present invention comprise alternativeintermediate sleeves to facilitate the gripping of the strain-reliefstrands 157 to provide strain relief.

Strain relief assembly 98 also includes a crimp sleeve 120 havingrespective front and back ends 122 and 124, and a central opening 126sized so that the crimp sleeve can slide over the outside ofintermediate sleeve 100. Crimp sleeve is preferably made of a relativelysoft metal such as copper so that it can be crimped over intermediatesleeve 100. Still further embodiments of the present invention comprisecrimp sleeves and/or intermediate sleeves of alternative materialssuitable for engaging one another and/or for providing strain relief.

Once fiber optic cable is prepared for connectorizing as shown in FIG.1, but with a fiber coating 152C removed to lengthen field fiber section152S. Strain relief assembly 98 is then ready to be incorporated intothe connector. In FIG. 2, strain-relief strands 157 are not included forease of illustration. FIG. 4 shows strain-relief strands 157 as beingtemporarily held back against cable 150 by crimp sleeve 120.

At the point of assembly shown in FIG. 2, lead-in tube 80 can be crimpedonto buffered layer 154 to provide initial stress relief while the partsmaking up strain-relief assembly 98 are added to the connector.

With continuing reference to FIG. 2 and as discussed above, intermediatesleeve 100 slips on over the exposed buffer layer 154 between lead-intube 80 and fiber optic cable 150. Intermediate sleeve 100 is thenplaced on ferrule holder back section 50B, where inner threads 108engage outer threads 64. Intermediate sleeve 100 is then threaded ontoferrule holder back section 50B and surrounds a portion thereof, therebyalso surrounding a portion of buffer layer 154 held in the ferrule backsection. Once intermediate sleeve 100 is in place as shown in FIG. 4,crimp sleeve 120 is moved to release strain-relief strands 157 heldthereby. Strain-relief strands 157 are then flared around grooved outersurface 112, as shown in FIG. 5. Note that in FIG. 5, connector 8includes an inner housing 210 that covers ferrule holder front end 50Fand cam 212 covering ferrule holder 50 at back section 50B but adjacentintermediate sleeve 100 and forward thereof.

With reference now to FIG. 6, crimp sleeve 120 is moved from its holdingplace on cable 150 to cover intermediate sleeve 100. This trapsstrain-relief strands 157 between the intermediate sleeve and the crimpsleeve, with grooves 114 on outer surface 112 of the intermediate sleeveserving to hold the strand ends in place.

Also as shown in FIG. 6, in the next step crimp sleeve 120 is crimped(e.g., hexagonally crimped), as illustrated by arrows 200. This squeezesthe intermediate sleeve and the crimp sleeve together, which serves tohold strain-relief strands 157 in place and provide stress relief. Italso causes gap 110 to at least partially close in certain embodimentsof the present invention, which serves to secure the intermediate sleeveto the ferrule holder, thereby providing further strain relief at backend 8B of connector 8.

FIG. 7 is an elevated perspective view of the connector similar to FIG.5, showing an inner housing 210 in place at the connector front end 8Fand crimp sleeve 120 in place over intermediate sleeve 100 at ferruleholder back section 50B.

Once intermediate sleeve 100 and crimp sleeve 120 are crimped in placeon ferrule holder back section 50B, a protective boot 220, temporarilystored over cable 150, is slid over connector back end 8B, as shown inthe side view of FIG. 8 and the elevated perspective view of FIG. 9.FIG. 9 also shows an outer housing or “shroud” 230 arranged over theinner housing 210 (see FIG. 7 and FIG. 8) at connector front end 8F.

Intermediate Sleeve Handler

Because intermediate sleeve 100 is relatively small (e.g., about 5 mm indiameter), it may prove difficult to handle when installingstrain-relief assembly 98 onto connector 8. Accordingly, with referenceto FIG. 10, the present invention includes an intermediate-sleevehandler (“handler”) 300 used to handle intermediate sleeve 100. Handler300 has front and back end faces 302 and 304 and a central hole 306centered on a central axis A_(H). Handler 300 includes a shelf 307between the central hole and back end face that serves as a stop againstwhich intermediate sleeve 100 abuts when placed within the handlercentral hole, as discussed below. Handler 300 has a smooth inner surface308, an outer surface 309, and a gap 310 in the outer surface and thatopens to the central hole to define a C-shape for the handler. Innersurface 308 includes opposing lips 311 on opposite sides of gap 310. Inan example embodiment, handler 300 includes one or more grooves 312 thatfacilitate gripping and handling the handler. Gap 310 is sized so thatit fits over the buffered section of a fiber optic cable.

Handler hole 306 is sized so that intermediate sleeve 100 can be easilypressed into the central hole at the handler front end face 302 with oneof the intermediate sleeve end faces (e.g., back end face 104) coming toa rest against shelf 307, and so that handler axis A_(H) andintermediate sleeve axis A_(S) are aligned, as shown in FIG. 11.

It is important that handler gap 310 line up with intermediate sleevegap 110, as best illustrated in FIG. 11. This can be done using afixture in the factory, or by keying the intermediate sleeve and theinstallation handler. One way to key these two components is byproviding flat sections 117 on the intermediate sleeve outer surfaceadjacent gap 110, and by providing corresponding flat sections (lips)311 on handler inner surface 108 so that these respective flat surfacesengage when the respective gaps line up. This engagement also serves tocause intermediate sleeve 100 to rotate along with handler 300 when thehandler is rotated (e.g., when threading the intermediate sleeve ontothe ferrule holder back section), rather than having the intermediatesleeve rotate independently within the handler.

To install intermediate sleeve 100 onto the back of connector 8 usinghandler 300, handler front face 302 faces ferrule back section 50B.Next, the aligned handler and intermediate sleeve gaps 310 and 110 areslid over the exposed buffer section 154 between the flared back end 84of lead-in tube 80 and oversized cable 150. Intermediate sleeve 100 isthen threaded onto ferrule holder back section 50F using handler 300.Handler 300 is then pulled back towards cable 150 and away fromconnector 8 until is it back at the exposed buffer section 154, where itcan be removed via gap 310. Since intermediate sleeve is held inposition on ferrule holder back section 50B by the engaged threads andwas held within handler 300 only with a slight press fit, the handlerand intermediate sleeve easily disengage when the handler is pulled awayfrom the ferrule back section.

The present invention has the advantage that it allows for properinstallation and strain relief of a field-installable fiber opticconnector directly on a fiber optic cable, such as an oversized fiberoptic cable, as opposed to being installed on the tight-buffered fiberportion inside the cable. This results in a more stable fiber opticcable termination.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A strain-relief assembly for a field-installable fiber opticconnector having a back end configured for connection to a fiber opticcable having a buffered portion and strain-relief strands, thestrain-relief assembly comprising: a ferrule holder having a backsection with an open back end and configured to accommodate the bufferedoptical fiber portion; an intermediate sleeve having an outer surfaceand configured to generally surround and engage a portion of the ferruleholder back section; a crimp sleeve having an inner surface, wherein thecrimp sleeve covers the intermediate sleeve with the strain-reliefstrands arranged between the crimp sleeve inner surface and theintermediate sleeve outer surface; and wherein the crimp sleeve gripsthe strain-relief strands between the crimp sleeve and the intermediatesleeve.
 2. The assembly of claim 1, wherein the crimp sleeve is adaptedto be crimped to grip the strain-relief strands between the crimp sleeveand the intermediate sleeve
 3. The assembly of claim 1, wherein theintermediate sleeve deforms when the crimp ring is crimped so as topermanently fix the intermediate sleeve to the ferrule holder backsection.
 4. The assembly of claim 1, wherein the intermediate sleeve hasa gap so that the intermediate sleeve is C-shaped, with the gap beingsized fit over the buffered portion.
 5. The assembly of claim 1,wherein: the ferrule holder back end has outer threads; and theintermediate sleeve has interior threads that match the outer threads sothat the intermediate sleeve can threadedly engage the ferrule backsection.
 6. The assembly of claim 1, wherein the intermediate sleeveouter surface includes grooves that assist in securing the strandsbetween the intermediate sleeve and the crimp sleeve.
 7. The assembly ofclaim 1, wherein at least one of the intermediate sleeve and the crimpsleeve comprises a metal.
 8. The assembly of claim 7, wherein theintermediate sleeve comprises aluminum and the crimp sleeve comprisescopper.
 9. The connector of claim 1, wherein at least one of theintermediate sleeve and the crimp sleeve is adapted for connection to anoversized fiber optic cable.
 10. A connector for a fiber optic cable,comprising: the strain relief assembly of claim 1, wherein the ferruleholder has a front end and the fiber optic cable comprises an opticalfiber; and a ferrule arranged in the ferrule holder front end, theferrule having a channel that holds a stub optical fiber having an endresiding within the ferrule channel and that interfaces with an end ofthe optical fiber of the fiber optic cable when the fiber optic cable isconnected to the connector.
 11. The connector of claim 10, furtherincluding a lead-in tube arranged in the open end of the ferrule holderback section and that facilitates inserting the optical fiber into theferrule holder channel.
 12. The connector of claim 11, furtherincluding: an outer housing that covers the ferrule holder front end;and a boot that covers the ferrule holder back end.
 13. A method ofproviding strain-relief in a connector for a fiber optic cable that hasan optical fiber section, a buffer section, strain-relief strands, and aprotective jacket, the method comprising: inserting the optical fibersection and buffered section into a back section of a ferrule holder;engaging an intermediate sleeve having inner and outer surfaces with theferrule holder back section so as to generally surround the ferruleholder back section; placing a plurality of the strain-relief strandsover the intermediate sleeve outer surface; placing a crimp sleevearound the intermediate sleeve and the strain-relief strands; andcrimping the crimp sleeve so as to secure the strain-relief strands andto fix the intermediate sleeve onto the ferrule holder back section. 14.The method of claim 13, wherein the intermediate sleeve is threaded andthe back section of the ferrule holder is threaded, and includingthreadedly engaging the intermediate sleeve with the ferrule holder. 15.The method of claim 13, wherein the intermediate sleeve includes a gapthat forms a C-shaped intermediate sleeve, and wherein said crimpingcauses the gap to at least partially close.
 16. The method of claim 13,wherein the ferrule holder has an open front end section and furtherincluding: arranging a ferrule and a splice assembly in the ferruleholder front end section, the ferrule having a ferrule channel and thesplice assembly having a splice assembly channel; providing a fiber stubin the ferrule and splice assembly channels; and interfacing an end ofthe fiber stub with an end of the cable optical fiber in the spliceassembly channel when the cable optical fiber section is inserted intothe back section of the ferrule holder.
 17. The method of claim 13,wherein engaging the intermediate sleeve with the ferrule holder backend includes: holding the intermediate sleeve in a handler adapted tohold the intermediate sleeve with a press fit; threading theintermediate sleeve onto the ferrule holder back section using thehandler to fix the intermediate sleeve on the ferrule holder backsection; and disengaging the handler from the intermediate sleeve andremoving the handler from the fiber optic cable.
 18. The method of claim13, further including: providing the intermediate sleeve bypre-installing the intermediate sleeve on the ferrule holder backsection.
 19. A strain-relieved connector for a fiber optic cable thathas an optical fiber with a front end, a buffered layer, andstrain-relief strands, the strain-relieved connector comprising: aferrule holder having a front section with an open front end and a backsection having an open back end, wherein the open front and back endsare connected by a ferrule holder channel; a ferrule and a spliceassembly arranged in the ferrule holder front end, the ferrule andsplice assembly having respective central channels; a fiber stub heldwithin the ferrule and splice assembly channels, wherein the fiber stubhas a back end residing in the splice assembly channel; the bufferedlayer held in the ferrule holder back section so that the fiber stubback end interfaces with the optical fiber front end within the spliceassembly channel; an intermediate sleeve that engages and generallysurrounds a portion of the ferrule holder back end section so as togenerally surround the buffered layer held therein; and a crimp sleevearranged around the intermediate sleeve so as to hold ends of thestrain-relief strands between the crimp sleeve and the intermediatesleeve, wherein the crimp sleeve grips the strain-relief strand endsbetween the crimp sleeve and the intermediate sleeve, wherein the crimpsleeve fixes the intermediate sleeve to the ferrule holder back end. 20.The connector of claim 19, wherein the crimp sleeve is adapted to becrimped to grip the strain-relief strands between the crimp sleeve andthe intermediate sleeve
 21. The connector of claim 19, wherein theferrule back section is threaded, wherein the intermediate sleeve isthreaded, and wherein the intermediate sleeve is threadedly engaged ontothe ferrule back section.
 22. The connector of claim 19, wherein theintermediate sleeve comprises aluminum and the crimp sleeve comprisescopper.
 23. The connector of claim 19, wherein the ferrule holder backsection is adapted to hold a buffered layer defining a 900 μm diameter.24. An intermediate sleeve handler apparatus for holding and handling anintermediate sleeve, the handler comprising: a C-shaped sleeve having aninner surface, an outer surface, front and back end faces, a centralhole having an central axis and connecting the front and back end facesand sized to press fit the intermediate sleeve, and a gap in the outersurface connected to the central hole that defines the C-shape and thatis sized to fit over a buffered section of a fiber optic cable; and ashelf arranged in the central hole that serves as a stop when theintermediate sleeve is press-fit into the central hole.
 25. The handlerof claim 24, wherein the intermediate sleeve includes a central axis, anouter surface, a gap, and respective flat sections on the outer surfaceon opposite sides of the gap, and wherein the apparatus further includesrespective lips formed on the inner surface on opposite sides of thehandler gap so as to engage the respective flat sections of theintermediate sleeve when the intermediate sleeve is inserted into thehandler central hole with the handler gap aligned with the intermediatesleeve gap.